Glow plate for internal combustion engine

ABSTRACT

A high thermal capacity plate and means for mounting the plate in the combustion chamber of an internal combustion engine. The mounting means maintains the plate in spaced and insulated relationship from the cooled surfaces so it will maintain a higher temperature to better vaporize fuel in the chamber.

United States Patent Silverstein 5]. May 13, 1975' [541 GLOW PLATE FORINTERNAL 2,473,254 6/1949 Morris 92/213 COMBUSTION ENGINE 2,478,2948/1949 Madsen 92/213 X Ab h 81 1810 3,489,130 1/1970 Polldan et a1123/193 CP [76] Inventor: ra am iverstein,

Metzeroth Rd Adelphiq Md 20783 FOREIGN PATENTS OR APPLICATIONS 731,6321/1943 Germany 92/224 1 1 P111991 1"- 19, 1973 778,119 3/1935 France123/193 P [21] App]. No.: 398,775

Primary Examiner-Manue1 A. Antonakas Assistant Examiner-Wi11iam C.Anderson [52] US. Cl. 123/193 CP; 92/176; 29/1565 Attorney, Agent, orpirm stevens Davis Miller & [51] Int. Cl F021 3/02; F02f 3/12 Mosher[58] Field of Search..... 123/193 CP, 193 P; 92/176,

[56] References Cited A high thermal capacity plate and means formounting the plate in the combustion chamber of an internal UNITEDSTATES PATENTS combustion engine. The mounting means maintains 1,405,8872/1922 Ail 92/176 X the plate in spaced and insulated relationship fromthe 59 2322 cooled surfaces so it will maintain a higher temperaort H 27/1929 Faroy et a]. 123/193 P ture to better vaponze fuel 1n thechamber. 2,075,388 3/1937 DeCloud 92/213 X 10 Claims, 8 Drawing FiguresSHEEI 2 BF 4 FIG.4

. 1 GLOW PLATE FOR INTERNAL COMBUSTION ENGINE BACKGROUND OF THEINVENTION This invention relates to internal combustion engines and moreparticularly to means for increasing the efficiency and decreasing thepollution output of such engines by maintaining the combustion chambertemperature at a higher level. The invention is especially useful indiesel engines but it is contemplated to be applicable to any types ofinternal combustion engines in which fuel is injected and burned by heatsuch as a conventional reciprocating diesel engine or a rotary enginesuch as the Wankel Engine.

It is well known in the art that high surface tempera tures within thecombustion chamber are desirable to promote better fuel vaporization,decrease carbon accumulation and decrease the emission of pollutants inthe exhaust gases since the higher temperatures will result in a muchhigher percentage of hydrocarbons being completely oxidized. Thisproduces higher engine effi' ciency, reduces fuel consumption and avoidsthe problems of attempting to decrease hydrocarbon exhaust content afterthe gases have left the engine. Despite the recognition of thedesirability of high surface temperatures within the combustion chamberthe prior art has experienced considerable difficulty in obtaining thisgoal.

RELATED PRIOR ART To accomplish the above results there must be somesort of insulation between the combustion chamber or parts thereof andthe remainder of the engine. In the past various types of coatingmaterials have been applied to the combustion chamber wall surfaces suchas in U.S. Pat. No. 3,552,370 of .Ian. 5, 1971 to Briggs. Other attemptshave included particulate insulating material imbedded in the top of thepiston such as in U.S. Pat. No. 3,149,409 of Sept. 22, I964 to Maruhn orthe securing of an insulating layer to the piston and combustion chamberwalls such as in U.S. Pat. No. 3,408,995 of Nov. 5, 1968 to Johnson.

The main difficulty with prior art attempts has been to produce adurable effective insulating liner which will remain adhered to thecombustion chamber walls and withstand the thermal expansion and thestresses of the combustion cycle.

PROBLEMS IN THE ART The problem of maintaining a high combustion chambertemperature is especially acute in diesel engines since a heavy liquidfuel is injected into the cylinder against the peak of internalcompression. Since the fuel is incompletely vaporized much of theburning takes place on the suspended fuel globules. Some fuel survivesburning and strikes the lubricated cylinder walls and degrades thelubricant to some extent. It is thus desirable to have a metal plateattached to the top of the diesel piston and insulated from it so thatit will remain at a higher temperature. Similarly the cylinder top canbe lined with a thermally conductive shell, insulated from the watercooled structure above. It is also advantageous that the piston strokeis markedly oversquare, that is, the stroke is shorter than the pistondiameter so that less cylinder wall will be exposed (and subsequentlydelubricated) in operation. Both a piston plate and a head liner willthen become glowing hot as the engine is run. Any heat which flows pastthe piston plate insulation will be dissipated by the piston skirtagainst the water cooled cylinder wall and also by the lubricating oil.Heat lost by the head liner is carried away by the water cooledstructure above.

THE PRESENT INVENTION The purpose of this invention is to provide athermally insulated lining for the firing chamber of a diesel engine.The stress problems of differential expansion, the looseness and flakingencountered in prior art attempts, are avoided.

A high thermal capacity material lining, preferably a metal, insulatedfrom the surrounding structure is attached to the piston top andpreferably also to the cylinder head. The linings can be fairly massiveplates of metal, having high thermal conductivity and capacity. In thecourse of operation the plates reach glowing temperature. They may becalled glow plates. A number of advantages follow from the cylinderinsulation, some of which have long been recognized. This inventionprovides a practical solution to the problem of insulating the glowplates and accommodating their expansion.

The underlying concept of this invention is to mount each glow plate oninsulated ways which lie along lines of expansion. By this means theglow plate is held with no play on a cooled piston top or cylinder head,but it can expand freely as it is heated. The concept will becomeclearer by examining some basic properties of uniform expansion.

SOME PROPERTIES OF UNIFORM EXPANSION A Disc Let the center of a disc beheld stationary with respect to a supporting plane. The disc alone isthen uniformly heated. The movement of any mark on the disc due toexpansion will be along a line through the mark and the center.

If another point, such as one on the periphery of the disc is heldstationary, the movement of a mark on the disc will be along a linethrough the stationary point and the mark.

Sliding ways, which permit only one direction of relative motion, areattached between the disc and support ing plane. They lie along theradial expansion lines from the fixed point. Then the disc can expandfreely, but it cannot be raised, moved off center, or rotated. The fixedpoint need not be attached. The convergence of the ways determines it.In principle, only two sliding ways determine the fixed point. The waysneed not extend across the width of the disc.

A Curved Lining The preceding is obviously applicable to the case of aglow plate covering the top of a diesel piston, with the center of theplate held fast. The glowing lining for the cylinder head will not ingeneral be flat, circular or even symmetrical, due to the placement ofvalves and injectors. On a homogeneous uniformly heated shell, curved inthree dimensions, the motion of a given point lies along a line from theselected stationary point through the given point. In general theexpansion lines for different points will lie in different planes, andso must the ways.

The convergence point of the expansion lines may lie outside theexpanding object. This case may be treated as if the object material hadbeen extended to that point.

If the shell is neither uniformly heated nor homogeneous, the stationarypoint is selected, and the ways placed along the measured lines ofexpansion.

According to this invention it is more desirable to provide a surfacewithin the combustion chamber which can be maintained at a highertemperature than it is to merely insulate the walls of the chamber. Thisinvention pertains to plates which, under operating conditions, will beglowing hot; thus the term glow plate as previously mentioned, will beused in the description herein.

In view of the above discussed problem, principal objects of the presentinvention are to provide an internal combustion engine, particularly adiesel engine, which will operate at a higher combustion chambertemperature leading to more efficient use of the fuel and fewerpolluting exhaust products.

Another object of this invention is to provide glow plate surfaceswithin the combustion chamber which will be hot enough to bettervaporize the fuel and promote spattering and more complete combustion ofit.

A further object of this invention is to provide means for mounting suchglow plates which will not only insulate them from the surroundingengine structure but also compensate for thermal expansion thereof.

DESCRIPTION OF A PREFERRED EMBODIMENT Other objects and advantages ofthis invention will become apparent from a review of the attacheddrawings which are furnished by way of example only and not oflimitation in order to illustrate a preferred embodiment in which:

FIG. 1 is a sectional view through a cylinder head and piston of aninternal combustion engine, the piston having a glow plate and securingmeans of the present invention;

FIG. 2 is a detailed cross section showing a modified means for securingthe glow plate to the top of the piston;

FIG. 3 is a sectional view along line 33 of FIG. 1;

FIG. 4 is a sectional view along line 44 of FIG. 1;

FIG. 5 is a sectional view through a cylinder head and piston of aninternal combustion engine, both the head and the piston having a glowplate according to the present invention attached thereto;

FIG. 6 is a plan view of the interior of the cylinder head;

FIG. 7 is a plan view of the top of the piston;

FIG. 8 is a cross section similar to FIG. 2 but of an alternativeembodiment.

Turning now to the drawings in greater detail, FIG. 1 shows a cylinder10 having a piston 12 mounted therein for reciprocal movement with awrist pin 14 se' curing it to a connecting rod 16 in a conventionalmanner. The cylinder 10 has a cylinder head 18 secured thereto also inconventional manner. A piston glow plate 22 is secured to the top of thepiston by the means of this invention as will be explained later indetail. Piston glow plate 22 preferably has an irregular surface 26 toincrease its surface area and promote better fuel vaporization and alsoto impede the flow of liquid fuel to the cylinder wall.

In the embodiment of FIG. 1 the glow plate 22 is secured to the top ofthe piston 12 by means of a downwardly projecting inverted V shapedportions 28 which fit into complimentary shaped sectors 30 formed in thetop of the piston. The widest part of the portion 28 is defined bycorners 32 and 34 and the distance between these corners is justslightly less than the distance between edges 36 and 38 of sector 30.

FIG. 3 shows that there are a plurality of inverted V- shaped portions28 around the circumference of the glow plate and the piston top; inthis particular instance six are shown for purposes of illustrationalthough the number may be varied as needed. To install the glow plateon the piston the glow plate is moved vertically into place so thatcorners 32 and 34 will fit between edges 36 and 38 of the sector. Piecesof insulation 40, 42 and 44 are then slid radially into place from theperiphery of the piston so as to surround the portion 28 and hold it inspaced and insulated relationship from the piston top. A wedge 46 isthen slid radially into place under insulation block of 44 so as tocompress that block against the under side of portion 28 which is inturn pushed against insulation pieces 40 and 42 so as to form a secureseating against the insulation, holding the glow plate rigidly in place.It is to be understood that the remaining portions around the peripheryof the piston are similarly secured. The remaining space between theunderside of the glow plate and the top of the piston is filled with asimilar insulation material 48, a compound sold under the name ofFibrefrax (A1 0 51.7%, SiO 47.6%) (a registered trademark of OwensCorning) being found to be quite satisfactory although any insulationmaterial which is relatively uncompressible, such as a ceramic material,could also be used. If necessary, the insulation 48 may be cemented tothe top of piston 12 by suitable cement 49 as seen in FIG. 2.

The wedges 44 are held in place by U-shaped springs 29 (see FIG. 4)which bear against the end of 48 of the wedge 46 to hold the wedgefirmly in place. The wedge is not as long as the opening or way in thesector 30, thus defining a space of 50 (see FIG. 4) between the distalend of the wedge and the end of the way. Thus, if any later compressionof any of the insulation pieces 40, 42 or 44 takes place, the wedge willbe forced farther along the way by the spring 29 and pick up theadditional space so that a rail portion 28 is still held firmly inplace.

Pieces of insulation 45 fill the space between the outer ends of rails28 and insulation pieces 40, 42 and 44 and band 27.

The U-shaped springs 29 are held in place by a suitable end coveringover the sectors 30; in the embodiment shown in FIGS. 1, 3 and 4 it isheld by a band 27 which is heat-shrunk over the piston to surround theend of the springs 29 to hold them securely in place.

FIG. 2 discloses a modified embodiment of the securing means shown inFIG. 1 in which the insulation pieces 40 and 42 have outer metal facings25 which are thick enough to make the upward stress on the insulationlargely compressive. Simultaneous compression perpendicular to thedirection of shear, strengthens the insulation in shear.

In the alternative arrangement of FIG. 8, the sector 31 which holds therail 28 has an entrance slot defined by edges 36 and 38 which isnarrower than the widest part of the rail 28. In this arrangement thesector 31 is a rectangular block with a V-shaped slot 33 which must beslid radially in from the end of the rail along with the insulation andthe spring loaded wedge. Sector 31 may be secured in the piston in asuitable slot or trough 35 with the aid of screws 37. It can be appliedwhen the end of the channel is not accessible for sliding in the end ofthe insulation. The open end of each channel must of course be closedand this can be done with an appropriate cross piece such as the band 27previously described. As previously indicated, any other space be tweenthe glow plate and the piston top is preferably also filled withinsulation 48. The insulation for the ways may be cut transversely,inserted in pieces as required. Transverse cuts without gaps causepractically no weakening since the insulation is contained by thechannel and is stressed in compression and transverse shear.

The preceding is obviously applicable to the case of the cylinder headliner 20 (see FIG. 5) which also acts as a glow plate covering the topof the combustion chamber. This liner will in general not be circular oreven symmetrical due to the placement of valves and injectors. On ahomogeneous uniformly heated shell secured in three dimensions, themotion of a point on the shell away from the stationary point will liealong a line between the two points. The ways along such lines will not,in general, lie in the same plane. As in the case of the piston, thedead space between the liner and the cooled cylinder head 19 should beminimized by filling it with insulation 21 adhering to the cylinderhead. If the shell is neither uniformly heated nor homogeneous, thestationary point should be selected and the insulated ways placed alongthe measured lines of expansion.

Rails 28 securing liner 20 to cylinder head 19 would preferably be ofthe cross-sectional shape of rail 28 shown in FIG. 2, but inverted. Thatis, with a flat upper surface and inclined sides sloping downwardly andinwardly to the vertical web. This avoids the stress concentration of arectangular head. This sloping transition also fixes the rail laterallywhen wedge pressure is applied even if the insulation is somewhat loosebefore pressure. The rail is no longer in contact area than thatrequired by strength. The temperature of the glow plate is of coursecontinual rather than intermittent during the cycle and thus theinsulation must be of the highest quality such as an adhesive refractoryinsulation similar to Fibrefrax (A1 5l.7%, SiO 47.6%) tamping mix.

Although it would be ideal to have all surfaces of the combustionchamber covered by the glow plates of the present invention, it isrealized that practical considerations such as complex shapes of thecombustion chamber may make this difficult. It is contemplated that aglow plate may be placed in only one part of the combustion chamber suchas on the head of the piston. In such case it would be desirable for theglow plate to have sufficient mass to store enough heat to maintain aproper temperature despite the possibility of heat loss through theuncovered surface areas of the combustion chamber.

In an embodiment such as shown in FIG. 5 where a head liner is used, theliner glow plate is held in place by rails 28 and wedges 46 which aresimilar in cross section to the rail 28 of FIGS. 1 and 2. A plurality ofthese rails are spaced around the periphery of the liner in a mannersimilar to that shown in FIGS. 3 and 4, that is the rails (and theirways) do not extend to the center of the liner. The ways may be cut intothe head to receive the corresponding rails and insulation is placedbetween the rails and ways, as in the manner previously described withsuitable sealing of the grooves afterwards.

It should be noted that the lower edge 23 of the head liner 20 extendsdown to overlap the raised rim 26 of the piston glow plate so that anyfuel globules spattered and vaporized against a glow plate surfacerather than against a cooled lubricated surface. The contour of the glowplate surfaces shown has been chosen to cause fuel particles or globulesto bounce from one to the other and especially to lead them away fromthe periphery of the piston to prevent unburned fuel from descendingalong the cylinder walls.

The above description is given by way of example only and is notconsidered to be a limitation of the scope of the invention which isdefined by the following claims.

What is claimed is:

1. A device for increasing the efficiency of an internal combustionengine having a cylinder and a moveable member therein comprising:

a. a thermally conductive plate carried by the moveable member saidplate and member having surfaces facing each other;

b. means between the plate and member to hold the plate in spaced apartrelation from the member while permitting thermal expansion of the platecomprising a plurality of discrete rail means projecting from one ofsaid surfaces along lines of thermal expansion of the plate, the othersurface having complementary rail retaining means receiving said railmeans.

2. The device of claim 1 in which the plate has sufficient mass to storeheat to vaporize fuel on contact therewith.

3. The device of claim 1 in which the outer surface of the plate isnon-planar to increase its surface area.

4. The device of claim 3 in which the non-planar surface has ridges todirect fuel and vapor axially in the cylinder.

5. The device of claim 1 including biasing means between the rail meansand the retaining means.

6. The device of claim 5 in which the biasing means is a wedge with aspring to maintain it in place.

7. The device of claim 1 including insulation means between the railmeans and the retaining means.

8. The device of claim 7 in which the insulation means comprises blocksof a hard non-compressible material having a metal sheath on at leastone side to facilitate insertion along the rail.

9. The device of claim 1 in which the rail means has a triangular crosssection with one side of the triangle facing toward the rail retainingmeans, the retaining means being a similar triangular shaped groovehaving a mouth slightly wider than said one side of the rail.

10. The device of claim 9 in which the cross sectional area of thetriangular shaped groove is greater than the cross sectional area of therail means with the space between them being filled with insulation.

2. The device of claim 1 in which the plate has sufficient mass to storeheat to vaporize fuel on contact therewith.
 3. The device of claim 1 inwhich the outer surface of the plate is non-planar to increase itssurface area.
 4. The device of claim 3 in which the non-planar surfacehas ridges to direct fuel and vapor axially in the cylinder.
 5. Thedevice of claim 1 including biasing means between the rail means and theretaining means.
 6. The device of claim 5 in which the biasing means isa wedge with a spring to maintain it in place.
 7. The device of claim 1including insulation means between the rail means and the retainingmeans.
 8. The device of claim 7 in which the insulation means comprisesblocks of a hard non-compressible material having a metal sheath on atleast one side to facilitate insertion along the rail.
 9. The device ofclaim 1 in which the rail means has a triangular cross section with oneside of the triangle facing toward the rail retaining means, theretaining means being a similar triangular shaped groove having a mouthslightly wider than said one side of the rail.
 10. The device of claim 9in which the cross sectional area of the triangular shaped groove isgreater than the cross sectional area of the rail means with the spacebetween them being filled with insulation.